Hi,
New to the forum. I just purchased a 1991 XJS Classic Collection convertible. I am having speedo issues. The speedo starts working around 20 mph but not before. Also the trip set and odometer do not work. I replaced the transducer cable that goes from the rear differential to the interface box in the trunk and it still does not work. I assume that that interface unit is possibly bad, but dont want to throw money away if thats not the problem. My interface unit part # is DAC 4591.
Any help would be much appreciated.
thanks Marc

 

Welcome to the forum ajsamantha,

I've moved your question from General Tech Help to XJS forum. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

It is unlikely to be the interface unit with this symptom, sounds more like a bad VR sensor or something mechanical in the speedo.

I would start by cleaning the connectors on interface unit especially the input side. Also remove the instrument cluster and clean the connectors on the rear. If this does not fix the issue I would suspect the VR sensor in the diff.

 

Warren,

Thanks = what is the VR sensor? I was also thinking the speedo head might be bad as I already removed cluster and cleaned the connectors and no help. I also did not mention that the temp gauge works sporatically. I have sourced a used cluster which I will install next week when it comes in and will keep you posted.
Thanks Marc

 

The VR sensor is the sensor in the diff. These generate a voltage and frequency that is proportional to speed, if the sensor is bad it might not generate enough voltage at low speed to register on the interface unit.

I would suspect the speedo first.

If you replace the cluster and still have the issue, jack the car and put it on stands so the rear wheels can rotate.

Start the car and put in gear, on the on the wires from speed interface to speedo you should see about 5volt AC on a multimeter.

 

Warren,
I will put in cluster first and see what happens. I will keep you posted.
Thanks Marc

 

Warren,
I will put in cluster when it arrives - will keep you posted.
Thanks Marc